1. Field of the Invention
The present invention relates to soap bar composition in which most or all of the soap has been replaced by other surfactants. Typically, when enough soap has been removed, the compositions are softer, stickier and accordingly more difficult to process. The present invention relates in particular to the use of small amounts of silicone or mixtures of silicones of defined viscosity (i.e., centistokes) which allow the detergent bars to be more efficiently processed.
2. Background
Traditionally, soap has been utilized as a skin cleaner. Soap is, however, a very harsh chemical. Irritated and cracked skin result from the use of soap, especially in colder climates. There are, however, certain benefits from the use of soap including less cost, ease of manufacture into bars, and good lathering properties.
Thus, there is a balance between attempting to replace soap with milder surfactants, on the one hand, and attempting to maintain manufacturing ease associated with use of soap on the other hand.
For example, if the amount and type of milder replacement surfactants which are added is too great, the soap pellets (i.e., chips) formed during manufacture (i.e., formed after mixing the ingredients, solidifying on a chill roll, and refining to form chips) will be too "soft". That is to say, the pellets or chips/noodles will melt on a valve used to transfer the chips to storage in a container/silo. Clogging the machinery such that the chips cannot be readily stored means that the process cannot be stopped and chips cannot be stored until a future time when the chips will be further mixed, refined, extruded, cut and stamped. That is, failure to allow storage means that the first part of the process cannot be run as a batch process (where chips can be stored) and must be run from mixing of ingredients until bar extrusion and stamping. This present invention is directed to those compositions which can be readily processed from chip formation to silo storage thereby allowing an intermediate storage step.
Typically such compositions are those in which the amount of soap used is at very low levels relative to surfactant, i.e., at level under 25% by weight of the composition, usually under 15% by weight.
Another way of looking at the problem is to determine when the composition of the pellets is sufficiently tacky that they clog machinery and lower throughput levels (i.e., rate of plodded bars coming out of a plodder) to economically unacceptable rates.
In applicants, co-pending application filed on the same day as the subject application and entitled "Low Soap Bar Composition Having Optimal Throughput at Lower Temperatures", applicants claim compositions wherein the throughput rate of a bar made from processing said composition through a plodder is higher at a temperature below 100.degree. F. than it is above 100.degree. F. This is unexpected in that normally it would not be possible to simultaneously process a bar at such high rates and at such low temperatures because the bar would be too hard, while at higher temperatures the bar would be too soft and not process at all.
While the compositions of the co-pending application are similar to those of the subject invention, there is no teaching in that application of adding specific silicone (i.e., of specific viscosity) in specific amounts in order to eliminate the problem of tacky pellets coming from the chill roll and refiner (e.g., so that they don't stick on the valve in the rotator) while passing the pellets/chips to a silo.
The use of silicone in bar compositions comprising silicone is known in the art, for example, from U.S. Pat. No. 5,154,849 to Visscher et al. (assigned to Procter & Gamble).
In the prior art compositions, silicone is used as a skin mildness/moisturizing aid and must be used in amounts sufficient to perceive these effects (e.g. from about 0.5% to about 20%). Thus, the silicone appears always to be used in amounts of at least several percents by weight (In the patent it is never exemplified at less that 5% as in Examples XII & XIII). There is certainly no recognition of a critical window not only in amount (i.e., from about 0.1 to about 0.9% by weight), but also in the viscosity of the silicone as in the silicone of the present invention. The Visscher patent also requires the presence of at least some silicone gum (claim 1) and this gum must have a molecular weight of at least 200,000 (claim 9). The silicone of the subject invention is used in the absence of gum and is not itself a silicone gum.